Gain affect in sound character

We are know if gain to increase amplitudo signal, so if we have high impedance headphone or speaker, we can drive it easyly. Beside to increase amplitudo signal, gain can change sound character from this amp too.

In this case i test gain affect in Little Dot MKIII. Little Dot MKIII have four setting gain. Gain 3,4,5,10. Gain 3 for low impedance headphone, gain 4 and 5 for medium and 10 for high impedance headphone.
My rig test is :

Source : CD transport Macbook
USB DAC : Fubar II USB DAC upgrade
Headamp : Little Dot MKIII upgrade
Headphone: AKG K501

Usually i use gain 4 to drive this headphone. Character from this gain is dinamic, transparant in mid and trebel. Volume in 10 clock is enough. After that i try to change gain to 3. Woww.. character change drastic, mid more warm, no hars in mid, soft treble and more slow tempo. I can't say this gain is more good, this is 2 gain with 2 different character. If u need sound with dinamic character, transparant go to high gain. But if you happy with sweet vocal go to low gain.